In the past, industrial chemicals, lubricants, oils and fuels, solvents, and other liquids have been packed in durable steel drums. Such drums can withstand extreme forces or friction exerted upon their curved side walls when lifting devices with pivotal grasping means are used to move the same. The rigid metal sides of such containers, particularly when filled with fluid or liquid, are built to withstand extreme friction force pressure.
Nowadays, many lubricants, chemicals and other fuels, are packed in plastic drums. Plastic drums are inexpensive to manufacture, resistant to rusting, cleaner to handle, and have a longer life. Unfortunately, plastic drums suffer one particular drawback. Such drums are fragile and have relatively resilient flexible sides compared to steel drums. Moreover, such barrels are easily punctured.
Previous lifting devices such as that described in Canadian Patent 606,745, are quite suitable for grasping and vertically lifting such things as heavy rolls of paper or steel cylinders. The extreme friction or force required to grasp and hold a pair of tongs firmly about the cylindrical sides of a roll of paper does not damage these items.
If one employs a device as shown in CP 606,745 (where the friction against the side walls is increased as the lifting force is increased) to lift a plastic drum, the result may be the caving-in and puncturing of the drum's relatively fragile sides.
It is therefore an object of the present invention to provide a lifting device for grasping and lifting plastic barrels without damaging the sides thereof.
It is a further object of the present invention to provide a device which can be both manually locked in a grasping/lifting/holding position and in an open position.
It is a further object of the present invention to provide a device which when secured and locked about a barrel, and an upward force is applied, the force is exerted upwardly below the lip of the top of the barrel rather than inwardly by means of friction on the sides of the barrel.